The invention relates to novel extracts obtained by extraction of ripe complete soya beans or from oil-free soya flour (Glycine max (L.) MERRIL, Leguminosae family), their production and formulations containing these extracts. The novel extracts are characterized by their content of isoflavones and saponins in defined ratios.
It is known that soya contains saponin and isoflavone components in addition to saccharide and amino acid components, as well as proteins and mineral salts in amounts which depend on their geographical origin and the conditions under which the plant was cultivated and harvested.
The saponin contents have been divided into three classes depending on the chemical structure of their triterpene components: soya saponins of groups A, B and E (Okubo K. et al., ACS Symp., Ser. 546, 330, 1994).
Isoflavone components consist of glucoside isoflavones (daidzin, genistin and glycitin) which can contain acyl radicals, e.g. malonyl radicals, linked to the saccharide chain.
According to biomedical literature and epidemiological information published in recent years, principally in relation to populations of the East, which consume soya-based foods to a great extent, the use of these foods to a high degree reduces pre-menopausal and post-menopausal symptoms in women (A. Cassidy, Proceedings of the Nutrition Society, 1996, 55, 339-417). These facts, which still lack a clear scientific basis, are usually ascribed to the isoflavone aglycones genistein, daidzein and glycitein, which are present in the various soya-based foods.
Isoflavones are usually considered to be plant oestrogens, and numerous in-vitro studies have shown that these substances act in a mechanism competing with mammalian oestrogens with an activity which is rated lower by a factor of 500 to 1000 than that of oestradiol (D. A. Shutt and R. I. Cox, Journal of Endocrinology, 1972, 52, 299-310).
According to further biomedical literature and epidemiological information published in recent years, principally relating to population groups in the East, which consume soya-based foods to a great extent, the use of these foods decreases to a high degree breast cancer in women and cancer of the prostate in men (A. Nomura, B. E., Henderson J. Lee, American Journal of Clinical Nutrition, 1978, 31, 2020-2025; T. Hirayama in Diet, Nutrition and Cancer, 1986 pp. 41-53, Y. Hayashi, M. Nagao, T. Sugimura, S. Takayama, L. Tomatis, L. W. Wattenberg and G. N. Wogan eds. Tokyo: Japanese Scientific Society Press; R. K. Severson, A. M. Y. Nomura, J. S. Grove, G. N. Stemmerman, Cancer Research, 1989, 49,1857-1860). Also, these facts, which still lack a clear scientific basis, are usually ascribed to the isoflavone aglycones genistein, daidzein and glycitein which are present in the various soya-based foods.
These isoflavones have been studied in in-vitro models with regard to their capacity to interact with protein kinases, in particular with tyrosine kinase, enzymes which appear to play a role in proliferation of tumour cells.
Numerous attempts have been made recently to prepare drugs based on soya extracts for the preventive treatment of pre-menopausal and post-menopausal symptoms and also for the preventive treatment of cancer. Some patents or patent applications describe compositions of novel soya extracts obtained by chemical or enzymatic hydrolysis of the glucoside isoflavones present in soya beans or soya bean sprouts (Kikkoman Corp. J-08291191; Kikkoman Corp J-07173148; Kelly GE WO-9323069; Kikkoman Corp. J-0511707566). All of these publications are concerned solely with the preparation of isoflavones of high concentration and activities with regard to the control of pre-menopausal and post-menopausal disorders and to antitumour activity.
It has now been found, that in contrast to that described previously, extracts which contain glucoside isoflavones and group B soya saponins in defined ratios are considerably more active than isoflavones alone as regards both, the prevention or treatment of pre-menopausal and post-menopausal symptoms and the prevention or treatment of cancer.
A further aspect related to the extract of the invention is concerned with alcohol abuse and alcohol dependency or alcohol addicition. These are phenomena which can be summarized under the term xe2x80x9calcoholismxe2x80x9d and form a serious problem of the entire modern society (Gessa G. L., xe2x80x9cBisogno compulsive di bere e principio del piacerexe2x80x9d [The compulsion to drink and the pleasure principle] in Medicina delle tossicodipendenze [Medicine of drug dependency] II, 5 (1994)). In Italy, for example, more than 9% of the population (about 5 million) are heavy drinkers and more than 1 million are alcohol-dependent (Calamo-Spechhia F. P., xe2x80x9cEpidemiologia dell""alcolismo in Italiaxe2x80x9d [Epidemiology of alcoholism in Italy] in Atti del VII Congresso Nazionale della S.I.A. [Reports of the 7th National Congress of the S.I.A.] Mediserve, Rome, 295-301 (1991)). These numbers are increased when countries such as the USA are taken into account, where more than 13 million are alcohol-dependent. Alcohol abuse and actual alcohol dependency lead to very high public expenditure (since 1991, in the USA about 200 billion dollars per year have been consumed) and are causes of great social and psychological damage to those affected.
Existing attempts to treat alcoholism in addition to those of a psychological nature (group therapy etc.) consist of applying drugs such as disulfiram and calcium carbamide, which act on alcohol metabolism, hepatic aldehyde dehydrogenase being inhibited and therefore the emetic acetaldehyde level being increased, together with all the unwanted phenomena which occur in the course of alcohol intake.
According to the prior art, the only plants whose derivatives were used for treating alcoholism are Pueraria lobata (Radix puerarie) and Salvia miltiorrhiza, which are very widely used in traditional Chinese medicine and form the subject-matter of the Patent Applications WO 93/00896 and WO 96/35441. In addition to the use of the extracts, these patent applications claim the use of pure substances such as daidzein and its semisynthetic derivatives in WO 93/00896, or diterpenoids, such as tanshinone and miltirone in WO 96/35441. An effect on alcohol dehydrogenase with the occurrence of the above-described side effect has been disclosed for the isoflavone derivatives, while the same mechanism has been excluded for the diterpenoid compounds. Furthermore, Patent Application WO 96/36332 disclosed the effect of forskolin in the reduction of alcohol consumption.
In addition to the above mentioned prior art WO 96/10341 discloses food or health products comprising substantially pure hypocotyls of soya seeds. No reference is made to the extraction procedure and to the ratio between isoflavones and saponins according to the present invention.
U.S. Pat. No. 4,428,876 discloses a process for isolating saponins and flavonoids from leguminous plants. The there disclosed extraction of soybean with 0.4% aqueous sodium hydroxide makes the final extract different from that of the present invention. Again, no reference is made to the ratio between isoflavones and saponins according to the present invention.
JP 59088064 is directed to the isolation and the use of saponins only. The same applies to DE 34 DO 258. Similarly JP 61036225 is directed to the isolation and purification of saponins and JP 62005917 to the preparation of pure saponins completely free of isoflavones. JP 4036242 concerns the preparation of pure saponin or of an extract having a high saponin/isoflavone ratio as an antiinflammatory compound.
EP-A-426 998 discloses the preparation of isoflavones from soybean and in particular of genistine and daidzine malonate. No reference is made to the extraction of saponins and to the ratio between isoflavones and saponins.
JP 63245648 is directed to the preparation of soybean food material devoid of saponins and isoflavones which are considered harshness components rendering the food unedible.
Mark Messina et al., Journal of the National Cancer Institute, Vol. 83, No. 8, Apr. 17, 1991, pages 541-546 is directed to the role of soy products in reducing risk of cancer already reported in scientific literature. Neither this document nor other literature, however, refer to an extract containing-saponins and isoflavones in the ratio of this invention, let alone the pharmacological effect obtainable by such a specific extract.
Suprisingly, it has now been found that extracts containing glucoside isoflavones and group B soya saponins in defined ratios can be used with success to reduce deliberate alcohol consumption. These extracts are significantly more effective than the isoflavones alone and act via a mechanism which is different from that of the inhibition of alcohol dehydrogenase, since the plasma alcohol level remains unchanged.
Thus, the invention relates to a soya extract having a content of glucoside isoflavones of at least 13% by weight and a content of 0.6 to 1.5 parts by weight of group B soya saponins per 1 part by weight of glucoside isoflavones. Preferably, the content of group B soya saponins is 1 part by weight per 1 part by weight of glucoside isoflavones.
The invention also relates to a pharmaceutical composition containing, as an active component, one of these soya extracts and a pharmaceutically acceptable carrier or diluent.
Another embodiment of the invention relates to methods for treating various conditions, such as pre- or post-menopausal symptoms in a female subject, cancer, such as breast cancer in a female subject or prostate cancer in a male subject, or alcoholism. The method step includes administering to a subject in need of such treatment a therapeutically effective amount of one of these soya extracts.
Yet another embodiment of the invention relates to a process for producing these soya extracts. This process comprises the steps of treating ripe whole soya beans or oil-free soya flour with an aliphatic alcohol to obtain a first extract; concentrating the first extract to form a concentrated first extract; purifying the concentrated first extract by treatment with at least one aliphatic hydrocarbon; and extracting active components from the purified concentrated first extract with a water-immiscible aliphatic alcohol to obtain a second extract.
Preferably, the process further comprises concentrating the second extract followed by drying to form the desired soya extract. Advantageously, the process further comprises adsorbing the second extract from the concentrated first extract to a polystyrene-based adsorption resin, flushing the resin with water, and eluting the second extract with ethanol. Additional preferred steps include suspending the first extract in a mixture of a water-miscible alcohol and water and diluting it with a water-immiscible aphotic solvent; heating the resulting mixture to complete dissolution and then holding it at room temperature to allow precipitation of group B soya saponins in a solution that contains an organic phase and an aqueous phase; collecting the precipitated group B soya saponins by filtration of the solution; separating the organic phase from the water phase, and then concentrating the organic phase and drying it to produce isoflavone components; and mixing the collected group B soya saponins with the isoflavone components to form the desired soya extract.